OBJECTIVES Adult patients with classic congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency have an increased risk of metabolic diseases. We aimed to investigate whether liquid chromatography-mass spectrometry (LC-MS)-based serum steroid profiling reveals metabolic phenotypes in adults with classic CAH.

DESIGN AND METHODS This study prospectively enrolled 63 adult patients with CAH and 38 healthy volunteers. The levels of the 24 steroids were quantified in the morning serum using LC-MS. Unsupervised clustering algorithms were applied to the serum steroid profiles to identify unique patterns associated with metabolic syndrome.

RESULTS Serum steroid profiles of patients with CAH were clearly delineated from those of healthy controls with a higher degree of interindividual heterogeneity. The unsupervised clustering algorithm divided CAH patients into two clusters based on serum steroid profile. Cluster 2 showed higher serum levels of glucocorticoids and androgens than cluster 1. The prevalence of metabolic syndrome was significantly higher in cluster 2 than in cluster 1 (37.8 % vs. 5.6 %, P = 0.011). Other clinical characteristics, including age, sex, body mass index, CAH subtypes, and glucocorticoid dose, did not differ between the two clusters. The multivariate logistic regression model of selective 15 steroids could discriminate metabolic syndrome in patients with CAH with an area under the receiver operating characteristic curve of 0.832 (95 % confidence interval:0.732-0.933).

CONCLUSIONS Serum steroid profiles can be valuable biomarkers for estimating metabolic risk in adult patients with CAH.